Imagine a farmer who has been sold the idea of allowing a wolf into the chicken coop to provide protection. How long would his flock survive the sharp teeth of a predator? Yet every day owners of buildings with galvanized metal roofs believe they are protecting against rust by using the very coating systems that encourage decay.

Manufacturers of various acrylic roof coatings cluck about their ability to ”freeze“ rust. But the fact is that while acrylics provide a cosmetic improvement, they actually absorb water and accelerate corrosion. What´s worse, some states like California actually have a ”cool roof“ policy, wherein white acrylics are encouraged. The law virtually guarantees that some building owners will eventually shell out big bucks to replace a destroyed metal roof.

Jack Taylor of Taylor Scientific in Missouri discovered this fact the hard way. About eight years ago his 20-year-old metal roof began showing signs of rust and had sprung a few minor leaks. The problems developed in all the usual places: around fasteners near the seams, and laps between the metal panels and at some of the flashing joints. A local contractor told him that an effective, inexpensive solution was to slather the 23,000-square-foot roof with a white acrylic coating.
”The installers of the white acrylic system assured me that their coatings would stop the rust and seal all the leaks and they gave me a ten year warranty against future leaks,“ Taylor recalls.

Four out of the ten years warranted later, the roof started to leak again. Taylor contacted the installers, asking them to honor the warranty. They returned and admitted that some extra rust had developed on the roof. Their solution? More of the same! They claimed that they had sealed the roof again, this time with extra thick acrylic mastic reinforced with a fabric. The leaks came back two years later – but not the contractor.
”I had trouble getting the acrylic installers to come back again, so I had to get quotes from other installers.“ he says, noting that the warranty was not backed by the manufacturer of the product.

Contractors who inspected the roof informed Taylor that the acrylic system he purchased had not been properly installed – not even the second time around. Also, he learned that many acrylic systems are incapable of providing the long-term protection he had hoped for.

To add insult to injury, the extra thick second coat actually caused more damage because it attracted even more moisture than the first coat. Further, the mesh fabric the installer used for reinforcement typically does not expand or stretch as the thermal cycle causes the metal roof to expand. As a result, the fabric bridges over the seams of a galvanized roof and creates small pockets that collect moisture and condensation. This promotes rust and deterioration.

While considering bids, Taylor learned about a roof system that begins with a Polyurethane sealer called Iron Sentry, which is applied to seams, holes and fasteners. The sealer cannot be penetrated by oxygen and water, even as it expands and contracts with the weather. It also is non-toxic: it contains no mercury. Best of all, the product came with a 10-year warranty from a 50 year old construction products manufacturer.

The manufacturer guarantees the warranty, but only after contractors agree to an inspection of the prep work. ”They can only can use our name if they agree to an inspection and apply product as we specify,“ says John Miller, general manager of Iron Sentry, which is a subsidiary of MCP Industries. He added, the comprehensive, front-loaded service with heavy emphasis on inspection and prep work adds enormous value to the system.

There was only one catch: a new roof system could not be installed until the mess created by the previous contractor was removed – at a hefty price. But Taylor, who decided to go with Miller´s product, is philosophical. ”Even with the higher cost of the Iron Sentry repair, refurbishment and Polyurethane coating, compared to the acrylic coating, it was still much less expensive than a complete metal roof replacement.“

Preventative Medicine is Green

When a building is purchased the owner knows that everything within that structure has a life cycle – plumbing, HVAC, electrical and the galvanized metal roof. Contractors say usually the roof is the item they have to deal with first because of the exposure to the elements.
Yet often building owners avoid roof repairs like most people avoid the dentist, and at their own detriment. Timely repairs not only rescue building owners from the reality Taylor avoided – an expensive complete metal roof replacement – they contribute to the Green movement, also known as sustainable design.
With the proper roof application, building owners are minimizing the life-cycle cost of maintaining the building and are minimizing the environmental impact. Why? Because they are using less new materials that eventually must be removed and disposed of in a landfill; and the product contains no mercury, which is a big issue with a lot of construction materials, according to industry sources.

The economic and environmental advantages expand for those building owners who choose the Iron Sentry system, because at a low cost the MCPU 10-year warranty is renewable and includes the Polyurethane sealer as well as a silver or white coating that is rolled on top of the entire roof.

If the warranty is meant to provide peace of mind for building owners, why is warranty renewal necessary? Miller says all roof systems – at least the top or ‘sacrificial´ layer of the system – will erode due to weather, especially acrylics. The Polyurethane sealer his firm sells will remain intact, but the silver or white coating that is rolled on top of the entire roof may need to be replaced. Better to do that at a minimal cost, he says, than use a system that will eventually have to be removed, leaving building owners like Taylor with no choice but to start over.

“The Iron Sentry installers removed all the thick old fabric reinforced acrylic, cut out and replaced badly rusted portions of the metal panels, sealed all the laps, joints and fasteners and applied a silver anti-corrosive and reflective top coat. The roof looks like a shiny new metal roof and there are no leaks. From the care they took in the repairs and installation, I expect Iron Sentry will honor their ten-year warranty in full,” says Taylor.